1. Field of the Invention
The present invention relates to automatic valve actuators or operators with provision for manual override operation.
2. State of the Art
It is well known to provide automatic actuators to operate valves for displacement to two or more desired positions. Typically, such automatic valve actuators utilize an electric motor which is coupled to a rotatable valve stem through a gear set. Such devices are used, for example, in systems which control the pumping, heating and filtration of water for swimming pools and spas. In such systems using automatic valve actuators, it is sometimes desirable to manually alter, or override, the setting of the valve. In typical prior art systems, manual override of a valve is accomplished by disconnecting the power to the valve drive motor and then manually engaging a valve displacement member to turn a rotatable portion of the valve together with the gear set and the rotor of the drive motor. Such a system is described, for example, in U.S. Pat. No. 2,550,906 to Britton.
One shortcoming of prior art manual override systems, such as ones shown in the patent to Britton, is that the systems are physically difficult to operate for a person of average strength, especially where the gear sets have substantial gear-reduction ratios. Nevertheless, a need frequently arises to manually override automatic valve operators; for example, the valve operators may need to be manually overridden for reasons of maintenance or simply to operate a system in a manner differently from the programmed mode of automatic operation.
Additionally, it is highly advantageous to be able to adjust the angular position or positions at which a valve operator stops the valve during its programmed or automatic operation. A diverter valve in a pool/spa system may be rotated, for example, to a position blocking the flow of water to the spa completely, or it may be more desirable to rotate the valve to a position blocking only 2/3 of the flow of water to the spa to permit some flow or blow-by to the spa. Prior art valve operators have not afforded the flexibility of easy adjustment of the valve angular positioning of the valve by the valve operator to accommodate variations between the respective pool and spa volumes from system to system. Instead, such prior valve operators have tended to depend upon the system controller and timing changes to accommodate the flow requirements as between the pool and spa and as between one pool/spa system and another.
Finally, it is typical for the plumbing portion of a pool/spa system to be constructed by one contractor while the automatic controls are installed by another. Thus, the valve operator installer is often faced with piping and valving which is coupled to direct water to the pool and the spa, but with no indication as to which position of the valve will produce flow to either the pool or the spa. The valve installer must install the valve operator, turn the system on. If the valve operator drives the valve to the "spa" position and water flows in fact to the pool, the valve operator must be rewired to reverse the flow so that the "spa" position corresponds to the flow of water to the spa. This rewiring on the job is time consuming and often results in the introduction of moisture into the electrical system of the valve operator with resultant corrosion.